young (surface)

The south polar region of Neptune's moon Triton
shows abundant signs of fairly recent resurfacing, possibly due in
part to geyser-like eruptions of nitrogen which could have brought
up darker materials from the crust

Descriptive of a planetary surface of which the visible features
are of relatively recent origin, older features have been destroyed by erosion,
lava flows, or other processes. Young surfaces exhibit few impact craters
and are typically varied and complex. In contrast, an "old" surface is one
that has changed relatively little over geologic time. The surfaces of Earth,
Io, and Europa,
for example, are young, whereas the surfaces of Mercury
and Callisto are old.